In JavaScript, an unoptimizing JIT (no regalloc, no optimizations that look at patterns of ops, no analysis) is faster than the interpreter because it eliminates opcode dispatch.
Adding more optimizations improves things from there.
But the point is, a JIT can be a speedup just because it isn’t an interpreter (it doesn’t dynamically dispatch ops).
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In JavaScript, an unoptimizing JIT (no regalloc, no optimizations that look at patterns of ops, no analysis) is faster than the interpreter because it eliminates opcode dispatch.
Adding more optimizations improves things from there.
But the point is, a JIT can be a speedup just because it isn’t an interpreter (it doesn’t dynamically dispatch ops).